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Carl Goldberg Yak 54 EP
The Carl Goldberg Yak 54 EP was a balsa/ply, park flyer-sized, fully aerobatic electric radio controlled airplane originally designed by Carl Goldberg Products, Ltd. of Oakville, Georgia USA. Intended for release in the latter part of 2006, the Yak 54 EP was in production in China during negotiations for the sale of the company to Champaign, Illinois-based hobby distributor Hobbico, finalized in August 2007. As a result of the negotiations, the model did not appear in the final independent Goldberg catalog nor did it appear in Hobbico's dealer newsletter, Great News. The model was added to both the Goldberg site as well as Great News in December 2007. One production unit, shown in the photograph, was pre-released for review by The E Zone, the online electric flight magazine of RCGroups.com. The prototype was designed and built in Russia by Yakovlev Design Bureau. First flown in 1993, the full-scale Yak 54 (also referred to as "Yak-54") is powered by a 360-horsepower radial engine. Only one is in service in the US. Known as Russian Thunder, its current owner is Jim Bourke, owner of RCGroups.com. Finished with four colors of Hobbico's Oracover covering, The Yak 54 EP came roughly 90 percent complete with its full hardware package, fully painted and finished fiberglass cowl, finished and framed Lexan canopy and a spiral-bound assembly manual. A computerized radio with a minimum of four channels, all onboard electronics, outrunner motor, electric propeller and spinner were required for completion. The model has since been discontinued by Great Planes. Flight characteristics As is the case with the prototype, the Yak 54 EP had generous control surfaces, light wing loading and light weight with nearly unlimited aerobatic capabilities. Elevator and rudder servos were externally mounted near the tail for longer, more precise throws. Each aileron had its own servo as well. Use of a computerized radio to slow down the response of the control surfaces resulted in a gentle flying aircraft which flew like a much larger model. However, too much reduction of the throws resulted in sluggish handling for even basic aerobatics. A radio with dual control rates gave a pilot the best of both a docile sport flier and fully aerobatic air show performer. The factory recommended power setup was adequate for straight and level flight, most basic aerobatics and 3-D performance, but overall performance is sluggish. A higher pitch propeller, such as a 11x6 or even a 11x7 was suitable for use with the recommended motor and greatly improved straight-line performance without sacrificing vertical performance; runtime was only slightly effected. The light wing loading also made for an extremely stable model at low airspeeds despite the lack of dihedral, which made the Yak 54 very easy to land with no observed tendency to tip stall. Specifications Servos, motor, battery, propeller and ESC were those recommended by the factory and flown in the RCGroups review model. *'Wingspan:' 40.25 in (1022 mm) *'Wing area:' 343 sq. in (22 sq. dm) *'Wing type:' Mid-mounted, semi-rectangular with symmetrical airfoil *'Weight:' 27-29 oz (765-822 g) *'Length:' 37.5 in (952.5 mm) *'Servos:' Futaba S3114 micro (FUTM0414) *'Battery:' Electrifly "Power Series" 1500mAh 3S lithium polymer (GPMP0613) *'Motor:' Electrifly Rimfire 35-30-950kv brushless outrunner (GPMG4590) *'Propeller:' APC 11x4.7 slo-flyer (LP 11047) *'Spinner as tested:' DU-BRO 2" black (273) *'ESC:' Electrifly Silver Series 25A brushless (GPMM1820) *'Catalog number:' GBGA1017 External links and references *Exclusive review of the Yak 54 at RCGroups.com *The Yak's home page under the discontinued models section at carlgoldbergproducts.com Category:Reviews Category:Aircraft